[CH2:1]([O:3][C:4]([C:6]1[N:7]=[C:8](Br)[O:9][CH:10]=1)=[O:5])[CH3:2].[C:12]([CH:14]1[CH2:16][CH2:15]1)#[CH:13].C(N(CC)CC)C>C1(C)C=CC=CC=1.Cl[Pd](Cl)([P](C1C=CC=CC=1)(C1C=CC=CC=1)C1C=CC=CC=1)[P](C1C=CC=CC=1)(C1C=CC=CC=1)C1C=CC=CC=1.[Cu]I>[CH:14]1([C:12]#[C:13][C:8]2[O:9][CH:10]=[C:6]([C:4]([O:3][CH2:1][CH3:2])=[O:5])[N:7]=2)[CH2:16][CH2:15]1
A mixture of 2-bromo-oxazol-4-carboxylic ethyl ester (0.967 g, 4.40 mmol, Combi-Blocks), trans-dichlorobis(triphenylphosphine)palladium (II) (0.201 g, 0.286 mmol, Strem) and copper (I) iodide (0.165 g, 0.866 mmol, Aldrich) in toluene (15 ml) was purged with argon for 10 min. Ethynylcyclopropane (1.00 ml, 11.80 mmol) and triethylamine (1.70 ml, 12.22 mmol) were added. After 2.5 h, the reaction mixture was partitioned between CH2Cl2 and water. The aqueous layer was extracted with CH2Cl2 (3×). The combined organic layers were washed with brine. The solvent was removed under reduced pressure and the residue and was purified by silica gel flash chromatography, eluting with (EtOAc):hexanes (0:1→2:3) to give 452 mg (50%) of a light-orange oil. MS m/z=206 [M+H]+. Calculated for C11H11NO3: 205.
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